From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757773AbbA2F2h (ORCPT ); Thu, 29 Jan 2015 00:28:37 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:55702 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752256AbbA2F2f (ORCPT ); Thu, 29 Jan 2015 00:28:35 -0500 Date: Thu, 29 Jan 2015 14:28:27 +0900 From: Minchan Kim To: Sergey Senozhatsky Cc: Sergey Senozhatsky , Andrew Morton , "linux-kernel@vger.kernel.org" , Linux-MM , Nitin Gupta , Jerome Marchand , Ganesh Mahendran Subject: Re: [PATCH v1 2/2] zram: remove init_lock in zram_make_request Message-ID: <20150129052827.GB25462@blaptop> References: <1422432945-6764-1-git-send-email-minchan@kernel.org> <1422432945-6764-2-git-send-email-minchan@kernel.org> <20150128145651.GB965@swordfish> <20150128233343.GC4706@blaptop> <20150129020139.GB9672@blaptop> <20150129022241.GA2555@swordfish> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150129022241.GA2555@swordfish> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 29, 2015 at 11:22:41AM +0900, Sergey Senozhatsky wrote: > On (01/29/15 11:01), Minchan Kim wrote: > > On Thu, Jan 29, 2015 at 10:57:38AM +0900, Sergey Senozhatsky wrote: > > > On Thu, Jan 29, 2015 at 8:33 AM, Minchan Kim wrote: > > > > On Wed, Jan 28, 2015 at 11:56:51PM +0900, Sergey Senozhatsky wrote: > > > > > I don't like re-introduced ->init_done. > > > > > another idea... how about using `zram->disksize == 0' instead of > > > > > `->init_done' (previously `->meta != NULL')? should do the trick. > > > > > > > > It could be. > > > > > > > > > > > care to change it? > > > > Will try! > > > > If it was your concern, I'm happy to remove the check.(ie, actually, > > I realized that after I push the button to send). Thanks! > > > > Thanks a lot, Minchan. > > and, guys, sorry for previous html email (I'm sure I toggled the "plain > text" mode in gmail web-interface, but somehow it has different meaning > in gmail world). > > > I'm still concerned about performance numbers that I see on my x86_64. > it's not always, but mostly slower. I'll give it another try (disable > lockdep, etc.), but if we lose 10% on average then, sorry, I'm not so > positive about srcu change and will tend to vote for your initial commit > that simply moved meta free() out of init_lock and left locking as is > (lockdep warning would have been helpful there, because otherwise it > just looked like we change code w/o any reason). > > what do you thunk? Surely I agreee with you. If it suffers from 10% performance regression, it's absolutely no go. However, I believe it should be no loss because that's one of the reason from RCU birth which should be really win in read-side lock path compared to other locking. Please test it with dd or something for block-based test for removing noise from FS. I also will test it to confirm that with real machine. Thanks for the review! > > -ss -- Kind regards, Minchan Kim